In recent years, home-use cogeneration apparatus have become popularly known which are constructed to not only supply electric power (electric) energy, generated by a power generator unit, to an electric load in conjunction with a commercial power system but also supply hot water (heat energy) or the like, generated using exhaust heat of an internal combustion engine, to a heat load.
In many home-use cogeneration apparatus, a gas engine is incorporated because gas is used as fuel. Basic principles of such a gas engine control device for controlling starting (activation) of the gas engine are disclosed in detail, for example, in Japanese Patent Application Laid-Open Publication No. HEI-08-42400.
In the gas engine, where rotational force is generated by explosion of a mixture of gas and air (i.e., air-fuel mixture), a crankshaft has to be rotated to cause such explosion. In order for the engine to shift from a non-running state to a running state in which the engine continues complete explosion of the air-fuel mixture, the air-fuel mixture must be exploded first by the crankshaft being rotated by some external means. The engine control device controls starting of the engine by so-called “cranking” indented to drive the crankshaft from the non-operating state via a starter motor.
As well known, a variety of gases are available as fuel today; in this country, for example, 13 types (seven groups) of town gases and types of LP gas are available, and the types of gases to be used are predetermined for individual pieces of equipment. An amount of generatable heat greatly differs not only among the types but also among groups even for a same type, and thus, if the number of types and groups of gasses (hereinafter also referred to simply as “gas types”) suited for the gas engine increases, appropriate starting of the engine may become difficult due to a cranking failure depending on the gas type used.